Technical Debt (TD) ( Technical Debt (TD) 1 / 23

Transcription

1 Technical Debt (TD) ( Technical Debt (TD) 1 / 23

2 Introducing the metaphor Technical Debt The term technical debt was coined by Ward Cunningham. ( Technical Debt (TD) 2 / 23

3 Introducing the metaphor Technical Debt The term technical debt was coined by Ward Cunningham. Used to describe the obligation that a software organization incurs when it chooses a design or construction approach that s expedient in the short term but that increases complexity and is more costly in the long term. ( Technical Debt (TD) 2 / 23

4 Introducing the metaphor Technical Debt The term technical debt was coined by Ward Cunningham. Used to describe the obligation that a software organization incurs when it chooses a design or construction approach that s expedient in the short term but that increases complexity and is more costly in the long term. The metaphor technical debt is used mainly to communicate the concept to technical staff, but it is more interesting to understand the metaphor s incredibly rich ability to explain a critical technical concept to non-technical project stakeholders. ( Technical Debt (TD) 2 / 23

5 What is Technical Debt (TD)?

6 What is Technical Debt (TD)? Two Basic Kinds First kind of TD is the kind that is incurred unintentionally. For example, a design approach just turns out to be error-prone or a junior programmer just writes bad code. This TD is the non-strategic result of doing a poor job. ( Technical Debt (TD) 3 / 23

7 What is Technical Debt (TD)? Two Basic Kinds First kind of TD is the kind that is incurred unintentionally. For example, a design approach just turns out to be error-prone or a junior programmer just writes bad code. This TD is the non-strategic result of doing a poor job. In some cases, this kind of debt can be incurred unknowingly. ( Technical Debt (TD) 3 / 23

8 What is Technical Debt (TD)?

9 What is Technical Debt (TD)? Two Basic Kinds First kind of TD is the kind that is incurred unintentionally. For example, a design approach just turns out to be error-prone or a junior programmer just writes bad code. This TD is the non-strategic result of doing a poor job. In some cases, this kind of debt can be incurred unknowingly. For example, your company might acquire a company that has accumulated significant technical debt that you don t identify until after the acquisition. Sometimes, ironically, this debt can be created when a team stumbles in its efforts to rewrite a debt-laden platform and inadvertently creates more debt. This is called a general category of debt - Type I TD. ( Technical Debt (TD) 3 / 23

10 What is Technical Debt? Two Basic Kinds...cont d Second kind of TD is the kind that is incurred intentionally. ( Technical Debt (TD) 4 / 23

11 What is Technical Debt? Two Basic Kinds...cont d Second kind of TD is the kind that is incurred intentionally. This commonly occurs when an organization makes a conscious decision to optimize for the present rather than for the future. ( Technical Debt (TD) 4 / 23

12 What is Technical Debt? Two Basic Kinds...cont d Second kind of TD is the kind that is incurred intentionally. This commonly occurs when an organization makes a conscious decision to optimize for the present rather than for the future. If we don t get this release done on time, there won t be a next release is a common refrain - and often a compelling one. ( Technical Debt (TD) 4 / 23

13 What is Technical Debt? Two Basic Kinds...cont d Second kind of TD is the kind that is incurred intentionally. This commonly occurs when an organization makes a conscious decision to optimize for the present rather than for the future. If we don t get this release done on time, there won t be a next release is a common refrain - and often a compelling one. Few examples ( Technical Debt (TD) 4 / 23

14 What is Technical Debt? Two Basic Kinds...cont d Second kind of TD is the kind that is incurred intentionally. This commonly occurs when an organization makes a conscious decision to optimize for the present rather than for the future. If we don t get this release done on time, there won t be a next release is a common refrain - and often a compelling one. Few examples This leads to decisions like, We don t have time to reconcile these two databases, so we ll write some glue code that keeps them synchronized for now and reconcile them after we ship. Or We have some code written by a contractor that doesn t follow our coding standards; we ll clean that up later. Or We didn t have time to write all the unit tests for the code we wrote the last 2 months of the project. We ll right those tests after the release. These are generally called as Type II TD. The rest of our discussion will focus on the kind of technical debt that s incurred for strategic reasons (Type II). ( Technical Debt (TD) 4 / 23

15 Short-Term vs. Long-Term Debt With real (a.k.a financial) debt, a company will maintain both short-term and long-term debt. You use short-term debt to cover things like gaps between your receivables (payments from customers) and expenses (payroll). You take on short term debt when you have the money, but you just don t have it now. Short-term debt is expected to be paid off frequently. Short-term debt is taken in anticipation that some good is in the pipeline shortly and it is mostly certain. Technical equivalent - Short-term debt is the debt that s taken on tactically and reactively, usually as a late-stage measure to get a specific release out the door. ( Technical Debt (TD) 5 / 23

16 Short-Term vs. Long-Term Debt With real (a.k.a financial) debt, a company will maintain both short-term and long-term debt. You use short-term debt to cover things like gaps between your receivables (payments from customers) and expenses (payroll). You take on short term debt when you have the money, but you just don t have it now. Short-term debt is expected to be paid off frequently. Short-term debt is taken in anticipation that some good is in the pipeline shortly and it is mostly certain. Technical equivalent - Short-term debt is the debt that s taken on tactically and reactively, usually as a late-stage measure to get a specific release out the door. These are called as Type II.A TDs. ( Technical Debt (TD) 5 / 23

17 Short-Term vs. Long-Term Debt...cont d Long term debt is the debt a company takes on strategically and proactively - investing in new capital equipment, like a new development center / research lab / corporate campus and in many other ways which may not always be infrastructure investments. Expanding the organization footprint in newer areas through innovation. For e.g., IoT. Technical equivalent : We don t think we re going to need to support a second platform for at least five years, so this release can be built on the assumption that we re supporting only one platform. These are called as Type II.B TDs. ( Technical Debt (TD) 6 / 23

18 Short-Term vs. Long-Term Debt...cont d Long term debt is the debt a company takes on strategically and proactively - investing in new capital equipment, like a new development center / research lab / corporate campus and in many other ways which may not always be infrastructure investments. Expanding the organization footprint in newer areas through innovation. For e.g., IoT. Technical equivalent : We don t think we re going to need to support a second platform for at least five years, so this release can be built on the assumption that we re supporting only one platform. These are called as Type II.B TDs. Implication to be Noted: Short-term debt should be paid off quickly, perhaps as the first part of the next release cycle, whereas long-term debt can be carried for a few years or longer. ( Technical Debt (TD) 6 / 23

19 Incurring Technical Debt When TD is incurred for strategic reasons, the fundamental reason is always that the cost of development work today is seen as more expensive than the cost will be in future. ( Technical Debt (TD) 7 / 23

20 Incurring Technical Debt When TD is incurred for strategic reasons, the fundamental reason is always that the cost of development work today is seen as more expensive than the cost will be in future. Reasons to Incur TD ( Technical Debt (TD) 7 / 23

21 Incurring Technical Debt When TD is incurred for strategic reasons, the fundamental reason is always that the cost of development work today is seen as more expensive than the cost will be in future. Reasons to Incur TD Time to Market When time to market is critical, incurring an extra $1 in development might equate to a loss of $10 in revenue. Even if the development cost for the same work rises to $5 later, incurring the $1 debt now is a good business decision. ( Technical Debt (TD) 7 / 23

22 Incurring Technical Debt When TD is incurred for strategic reasons, the fundamental reason is always that the cost of development work today is seen as more expensive than the cost will be in future. Reasons to Incur TD Time to Market When time to market is critical, incurring an extra $1 in development might equate to a loss of $10 in revenue. Even if the development cost for the same work rises to $5 later, incurring the $1 debt now is a good business decision. Preservation of Startup Capital In a startup environment you have a fixed amount of seed money, and every dollar counts. If you can delay an expense for a year or two you can pay for that expense out of a greater amount of money later rather than out of precious startup funds now. ( Technical Debt (TD) 7 / 23

23 Incurring Technical Debt...cont d Reasons to Incur TD... Delaying Development Expense When a system is retired, all of the system s technical debt is retired with it. ( Technical Debt (TD) 8 / 23

24 Incurring Technical Debt...cont d Reasons to Incur TD... Delaying Development Expense When a system is retired, all of the system s technical debt is retired with it. Once a system has been taken out of production, there s no difference between a clean and correct solution and a quick and dirty solution. ( Technical Debt (TD) 8 / 23

25 Incurring Technical Debt...cont d Reasons to Incur TD... Delaying Development Expense When a system is retired, all of the system s technical debt is retired with it. Once a system has been taken out of production, there s no difference between a clean and correct solution and a quick and dirty solution. How it is DIFFERENT then financial debt? When a system is retired all its technical debt is retired with it. ( Technical Debt (TD) 8 / 23

26 Incurring Technical Debt...cont d Reasons to Incur TD... Delaying Development Expense When a system is retired, all of the system s technical debt is retired with it. Once a system has been taken out of production, there s no difference between a clean and correct solution and a quick and dirty solution. How it is DIFFERENT then financial debt? When a system is retired all its technical debt is retired with it. To Remember: Near the end of a system s service life it becomes increasingly difficult to cost-justify investing in anything other than what s most expedient. ( Technical Debt (TD) 8 / 23

27 Be Sure You Are Incurring The RIGHT Kind of TD Some debt is taken on in large chunks: Type II.A.1 We don t have time to implement this the right way; just hack it in and we ll fix it after we ship. Conceptually, this is like buying a car - it s a large debt that can be tracked and managed. ( Technical Debt (TD) 9 / 23

28 Be Sure You Are Incurring The RIGHT Kind of TD Some debt is taken on in large chunks: Type II.A.1 We don t have time to implement this the right way; just hack it in and we ll fix it after we ship. Conceptually, this is like buying a car - it s a large debt that can be tracked and managed. Other category: Type II.A.2 Debt also accumulates from taking hundreds or thousands of small shortcuts - generic variable names, sparse comments, creating one class in a case where you should create two, not following coding conventions, and so on. ( Technical Debt (TD) 9 / 23

29 Be Sure You Are Incurring The RIGHT Kind of TD Some debt is taken on in large chunks: Type II.A.1 We don t have time to implement this the right way; just hack it in and we ll fix it after we ship. Conceptually, this is like buying a car - it s a large debt that can be tracked and managed. Other category: Type II.A.2 Debt also accumulates from taking hundreds or thousands of small shortcuts - generic variable names, sparse comments, creating one class in a case where you should create two, not following coding conventions, and so on. Equivalence: This kind of debt is like credit card debt. ( Technical Debt (TD) 9 / 23

30 Be Sure You Are Incurring The RIGHT Kind of TD Some debt is taken on in large chunks: Type II.A.1 We don t have time to implement this the right way; just hack it in and we ll fix it after we ship. Conceptually, this is like buying a car - it s a large debt that can be tracked and managed. Other category: Type II.A.2 Debt also accumulates from taking hundreds or thousands of small shortcuts - generic variable names, sparse comments, creating one class in a case where you should create two, not following coding conventions, and so on. Equivalence: This kind of debt is like credit card debt. Remember and Be CAREFUL: It s easy to incur unintentionally, it adds up faster than you think, and it s harder to track and manage after it has been incurred. ( Technical Debt (TD) 9 / 23

31 Be Sure You Are Incurring The RIGHT Kind of TD Some debt is taken on in large chunks: Type II.A.1 We don t have time to implement this the right way; just hack it in and we ll fix it after we ship. Conceptually, this is like buying a car - it s a large debt that can be tracked and managed. Other category: Type II.A.2 Debt also accumulates from taking hundreds or thousands of small shortcuts - generic variable names, sparse comments, creating one class in a case where you should create two, not following coding conventions, and so on. Equivalence: This kind of debt is like credit card debt. Remember and Be CAREFUL: It s easy to incur unintentionally, it adds up faster than you think, and it s harder to track and manage after it has been incurred. Both kinds of TDs - Type II.A.1 and Type II.A.2 are commonly incurred in response to the directive to Get it out the door as quickly as possible. ( Technical Debt (TD) 9 / 23

32 Be Sure You Are Incurring The RIGHT Kind of TD Some debt is taken on in large chunks: Type II.A.1 We don t have time to implement this the right way; just hack it in and we ll fix it after we ship. Conceptually, this is like buying a car - it s a large debt that can be tracked and managed. Other category: Type II.A.2 Debt also accumulates from taking hundreds or thousands of small shortcuts - generic variable names, sparse comments, creating one class in a case where you should create two, not following coding conventions, and so on. Equivalence: This kind of debt is like credit card debt. Remember and Be CAREFUL: It s easy to incur unintentionally, it adds up faster than you think, and it s harder to track and manage after it has been incurred. Both kinds of TDs - Type II.A.1 and Type II.A.2 are commonly incurred in response to the directive to Get it out the door as quickly as possible. Better Avoided: the second kind (II.A.2) doesn t pay off even in the short term of an initial development cycle and should be avoided. ( Technical Debt (TD) 9 / 23

33 Debt Service Important Implications Important implication of TD is that it must be serviced, i.e., once you incur a debt there will be interest charges. ( Technical Debt (TD) 10 / 23

34 Debt Service Important Implications Important implication of TD is that it must be serviced, i.e., once you incur a debt there will be interest charges. If debt grows large enough, eventually the company will spend more on servicing its debt than it invests in increasing the value of its other assets. Common example is a legacy code base in which so much work goes into keeping a production system running (i.e., servicing the debt ) that there is little time left over to add new capabilities to the system. Analogy to Financial Debt - Key Ratios With financial debt, analysts talk about the debt ratio, which is equal to total debt divided by total assets. Higher debt ratios are seen as more risky, which seems true for technical debt, too. ( Technical Debt (TD) 10 / 23

35 Attitude Towards Technical Debt Like financial debt, different companies have different philosophies about the usefulness of debt. Some companies want to avoid taking on any debt at all; Others see debt as a useful tool and just want to know how to use debt wisely. It is found that business staff generally seems to have a higher tolerance for technical debt than technical staff does. Common Belief: Business executives tend to want to understand the trade-offs involved, whereas some technical staff seem to believe that the only correct amount of technical debt is zero. ( Technical Debt (TD) 11 / 23

36 Attitude Towards Technical Debt...cont d Difficulty 1: The reason most often cited by technical staff for avoiding debt altogether is the challenge of communicating the existence of technical debt to business staff and the challenge of helping business staff remember the implications of the technical debt that has previously been incurred. ( Technical Debt (TD) 12 / 23

37 Attitude Towards Technical Debt...cont d Difficulty 1: The reason most often cited by technical staff for avoiding debt altogether is the challenge of communicating the existence of technical debt to business staff and the challenge of helping business staff remember the implications of the technical debt that has previously been incurred. Difficulty 2: Everyone agrees that it s a good idea to incur debt late in a release cycle, but business staff can sometimes RESIST accounting for the time needed to pay off the debt on the next release cycle. ( Technical Debt (TD) 12 / 23

38 Attitude Towards Technical Debt...cont d Difficulty 1: The reason most often cited by technical staff for avoiding debt altogether is the challenge of communicating the existence of technical debt to business staff and the challenge of helping business staff remember the implications of the technical debt that has previously been incurred. Difficulty 2: Everyone agrees that it s a good idea to incur debt late in a release cycle, but business staff can sometimes RESIST accounting for the time needed to pay off the debt on the next release cycle. Difficulty 3: The main issue seems to be that, unlike financial debt, technical debt is much less visible, and so people have an easier time ignoring it. ( Technical Debt (TD) 12 / 23

39 How to make an Organization s Debt Load More Visible? Possible Solution 1 Organization can maintain TD list within its defect tracking system. Each time a debt is incurred, tasks needed to pay off that debt are entered into the system along with an estimated effort and schedule. Debt backlog is then tracked, and any unresolved debt more than 90 days old is treated as critical. ( Technical Debt (TD) 13 / 23

40 How to make an Organization s Debt Load More Visible? Possible Solution 1 Organization can maintain TD list within its defect tracking system. Each time a debt is incurred, tasks needed to pay off that debt are entered into the system along with an estimated effort and schedule. Debt backlog is then tracked, and any unresolved debt more than 90 days old is treated as critical. Possible Solution 2 Organization can maintain its debt list as part of its Scrum product backlog, with similar estimates of effort required to pay off each debt. Many other solutions may exists... varying from org. to org. ( Technical Debt (TD) 13 / 23

41 How to make an Orgs. Debt Load More Visible?...cont d Either of previous TWO approaches can be used to increase visibility into the debt load and into the debt service work that needs to occur within or across release cycles. Each also provides a useful safeguard against accumulating the credit card debt of a mountain of tiny shortcuts mentioned earlier. ( Technical Debt (TD) 14 / 23

42 How to make an Orgs. Debt Load More Visible?...cont d Either of previous TWO approaches can be used to increase visibility into the debt load and into the debt service work that needs to occur within or across release cycles. Each also provides a useful safeguard against accumulating the credit card debt of a mountain of tiny shortcuts mentioned earlier. Lesson to Remember: As an Architect You can simply tell the team, If the shortcut you are considering taking is too minor to add to debt-service defect list/product backlog, then it s too minor to make a difference; don t take that shortcut. We only want to take shortcuts that we can track and repair later.. ( Technical Debt (TD) 14 / 23

43 Ability to Take on Debt Safely Varies Different teams will have different TD credit ratings. The credit rating reflects a team s ability to pay off technical debt after it has been incurred. A key factor in ability to pay off TD is the level of debt a team takes on unintentionally, i.e., how much of its debt is Type I? The less debt a team creates for itself through unintentional low-quality work, the more debt a team can safely absorb for strategic reasons. All of above is true regardless of whether we re talking about taking on Type I vs. Type II debt, or Type II.A.1 vs. Type II.A.2 debt. ( Technical Debt (TD) 15 / 23

44 Ability to Take on Debt Safely Varies...cont d One company tracks debt vs. team velocity. Once a team s velocity begins to drop as a result of servicing its technical debt, the team focuses on reducing its debt until its velocity recovers. ( Technical Debt (TD) 16 / 23

45 Ability to Take on Debt Safely Varies...cont d One company tracks debt vs. team velocity. Once a team s velocity begins to drop as a result of servicing its technical debt, the team focuses on reducing its debt until its velocity recovers. Another approach is to track rework, and use that as a measure of how much debt a team is accumulating. ( Technical Debt (TD) 16 / 23

46 Ability to Take on Debt Safely Varies...cont d One company tracks debt vs. team velocity. Once a team s velocity begins to drop as a result of servicing its technical debt, the team focuses on reducing its debt until its velocity recovers. Another approach is to track rework, and use that as a measure of how much debt a team is accumulating. How you address these issues in Samsung? How we should take this in the context of Architecture? ( Technical Debt (TD) 16 / 23

47 Retiring Debt Working off debt can be motivational and good for team morale. A good approach when short-term debt has been incurred is to take the first development iteration after a release and devote that to paying off short-term technical debt. ( Technical Debt (TD) 17 / 23

48 Retiring Debt Working off debt can be motivational and good for team morale. A good approach when short-term debt has been incurred is to take the first development iteration after a release and devote that to paying off short-term technical debt. The ability to pay off debt depends at least in part on the kind of software the team is working on. If a team incurs short-term debt on a web application, a new release can easily be rolled up after the team backfills its debt-reduction work. If a team incurs short-term debt in avionics firmware - the pay off of which requires replacing a box on an airplane - that team should have a higher bar for taking on any short-term debt. An Analogous Scenario This is like a minimum payment - if your minimum payment is 3% of your balance, that s no problem. If the minimum payment is $1000 regardless of your balance, you d think hard about taking on any debt at all. ( Technical Debt (TD) 17 / 23

49 Communicating about Technical Debt TD vocabulary provides a way to communicate with non-technical staff in an area that has traditionally suffered from a lack of transparency. Shifting the dialog from a technical vocabulary to a financial vocabulary provides a clearer, more understandable framework for these discussions. ( Technical Debt (TD) 18 / 23

50 Communicating about Technical Debt TD vocabulary provides a way to communicate with non-technical staff in an area that has traditionally suffered from a lack of transparency. Shifting the dialog from a technical vocabulary to a financial vocabulary provides a clearer, more understandable framework for these discussions. Although the TD terminology is not currently in widespread use, it is found that it resonates immediately with every executive as well as other non-technical stakeholders. It also makes sense to technical staff who are often all-too-aware of the debt load their organization is carrying. ( Technical Debt (TD) 18 / 23

51 Suggestions on Communicating about TD...cont d To non-technical stakeholders: Use an organization s maintenance budget as a rough proxy for it s TD service load. Important: 1 You will need to differentiate between maintenance that keeps a production system running / working Vs. 2 Maintenance that extends capabilities of a production system. Remember: Only the first category counts as TD. ( Technical Debt (TD) 19 / 23

52 Suggestions on Communicating about TD...cont d To non-technical stakeholders: Use an organization s maintenance budget as a rough proxy for it s TD service load. Important: 1 You will need to differentiate between maintenance that keeps a production system running / working Vs. 2 Maintenance that extends capabilities of a production system. Remember: Only the first category counts as TD. Discuss debt in terms of financials rather than in terms of features. For example, 40% of our current R&D budget is going into supporting previous releases or We re currently spending $2.3 million per year servicing our TD. ( Technical Debt (TD) 19 / 23

53 Suggestions on Communicating about TD...cont d Be sure you re taking on the right kind of debt. Not all debts are equal. Some debts are the result of good business decisions; others are the result of sloppy technical practices or bad communication about what debt the business intends to take on. The only kinds that are really healthy are Types II.A.1 and II.B. Treat the discussion about debt as an ongoing dialog rather than a single discussion. You might need several discussions before everyone fully sink in to understand TD. ( Technical Debt (TD) 20 / 23

54 Summary: Technical Debt Taxonomy Non Debt Deferred features, cut features, etc. Not all incomplete work is debt. These aren t debt, because they don t require interest payments. Debt I. Debt incurred unintentionally due to low quality work II. Debt incurred intentionally II.A. Short-term debt, usually incurred reactively, for tactical reasons II.A.1. Individually identifiable shortcuts (like a car loan) II.A.2. Numerous tiny shortcuts (like credit card debt) II.B. Long-term debt, usually incurred proactively, for strategic reasons ( Technical Debt (TD) 21 / 23

55 Summary of Today s Discussion What do you think? Do you like the technical debt metaphor? Do you think it s a useful way to communicate the implications of technical/business decision making to non-technical project stakeholders? What s your experience? Let us here your thoughts. Note This discussion is entirely based on list of resources mentioned in the next slide. ( Technical Debt (TD) 22 / 23

56 Resources Article posted by Steve McConnell Software Development/Technical Debt/ Ward Cunningham s OOPSLA 92 Experience Report that first mentions technical debt. Martin Fowler s brief bliki entry about technical debt. c2 wiki discussions of Complexity As Debt and Technical Debt. ( Technical Debt (TD) 23 / 23